Implant for embolization

Abstract

The present application relates to a kind of embolism implants for treating carotid internal carotid cavernous fistula, including flow blocking component and the braided stent body of self-expanding;The flow blocking component is set on stent body;The embolism implant has expanded state and stretched state, and can be switched between expanded state and stretched state, and the embolism implant forms the double-layer curved surface structure of circumferential non-closure after expansion, so that the embolism implant is better, and the risk of internal leakage is reduced, and more blood vessels can be applied.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of medical devices, and particularly relates to an implant for embolization of carotid cavernous fistula. BACKGROUND

[0002] Carotid cavernous fistula (CCF for short) refers to an abnormal arteriovenous shunt formed between the carotid artery or its branch of the cavernous sinus segment and the cavernous sinus after the rupture, which leads to increased pressure in the cavernous sinus, and then causes corresponding symptoms of the orbital and central nervous system. According to the cause, it can be divided into traumatic CCF (TCCF for short) and spontaneous CCF; according to the flow rate of the fistula, it can be divided into high-flow fistula and low-flow fistula; high-flow fistula is mostly caused by trauma, and low-flow fistula is mostly spontaneous, of which high-flow fistula caused by trauma accounts for more than 75% of carotid cavernous fistula.

[0003] The treatment of carotid cavernous fistula is relatively complex. For medium fistulas, a detachable balloon can be used to enter the fistula to fill and embolize, although the cure rate is relatively high, such as more than 85%, but it cannot be applied to small fistulas, and the treatment of curved segment fistulas is difficult, the recurrence rate is high, and the balloon is easy to shift, and there is a risk of early leakage or rupture, which leads to the risk of fistula recanalization; for larger fistulas, balloon-assisted coil and glue embolization is used, a large coil is first used to form a frame at the fistula, and then dense filling is performed as close to the fistula as possible, and then glue is used to seal the fistula, but the cavernous sinus cavity is large, and after dense filling, there may be a space-occupying effect that affects the surrounding blood vessels or nerves, and there is also a risk of coil protruding into the carotid artery, which increases the risk of carotid artery occlusion, and glue may overflow, which may block the ophthalmic artery or central retinal artery, causing permanent blindness, and non-dense embolization may lead to the risk of fistula recurrence later. With the development of new technologies, balloon-expandable covered stents have been gradually applied to the treatment of carotid cavernous fistula, which can seal the fistula at one time, but the hardness is relatively large, the flexibility is poor, and it is difficult to accurately position the over-curved carotid artery, especially when the fistula is at the turning point of the carotid artery, the embolization implant is difficult to completely seal it, which may have the risk of internal leakage. Therefore, the traditional balloon-expandable covered stent is not suitable for patients with curved arteries, and the risk of internal leakage is high.

[0004] Therefore, there is an urgent need for a new embolization implant to make the stent device applicable to patients with curved blood vessels and reduce the risk of internal leakage. SUMMARY

[0005] The purpose of the present application is to provide an embolization implant to solve the problems of poor flexibility, unsuitability for curved blood vessels, and high risk of internal leakage of the traditional balloon-expandable covered stent in the background art.

[0006] To achieve the above object, the present application provides an implant for embolization, used for treating carotid-cavernous fistula, comprising a flow-blocking component and a self-expandable braided stent body; the flow-blocking component is arranged on the stent body; the implant for embolization has an expanded state and a stretched state, and can switch between the expanded state and the stretched state; wherein the implant for embolization forms a circumferentially non-closed double-layer curved surface structure after expansion.

[0007] In an embodiment, the double-layer curved surface structure has a closed torus cross section, and the flow-blocking component is clamped in the closed torus.

[0008] In an embodiment, the flow-blocking component is connected to the proximal end and / or distal end of the stent body in the axial direction.

[0009] In an embodiment, the distal end portion of the stent body is a distal end bevel extending in the axial direction to the distal end.

[0010] In an embodiment, all the braided wires on the stent body are reversely wound in the axial direction of the stent body at the distal end to form a smooth distal end face.

[0011] In an embodiment, the proximal end portion of the stent body is a proximal end bevel extending in the axial direction to the proximal end.

[0012] In an embodiment, all the braided wires on the stent body are reversely wound in the axial direction of the stent body at the proximal end to form free wire heads, and all the free wire heads converge and are fixed by a proximal end connecting portion.

[0013] In an embodiment, the proximal end connecting portion is a radiopaque structure, and the radiopaque structure wraps all the free wire heads.

[0014] In an embodiment, the inner surface and / or outer surface of the flow-blocking component is provided with a drug coating.

[0015] In an embodiment, the flow-blocking component is made of a degradable film.

[0016] In an embodiment, the flow-blocking component is made of a film, and the thickness of the film is 5 μm-100 μm.

[0017] In an embodiment, the thickness of the film is 5 μm-50 μm.

[0018] In an embodiment, the curvature of the double-layer curved surface structure is adapted to the diameter of the target lumen, and when expanded in a natural state, the curvature of the double-layer curved surface structure is not less than 2 / 3π.

[0019] In an embodiment, the curvature of the double-layer curved surface structure is no more than π when expanded in a natural state, and the curvature of the double-layer curved surface structure is more than π when expanded under the constraint of the target lumen.

[0020] In an embodiment, the total axial length of the embolization implant when expanded in a natural state is 15mm-55mm, and / or the maximum diameter of the embolization implant when expanded in a natural state is 3mm-6mm.

[0021] In an embodiment, the axial length of the proximal end portion and the distal end portion of the stent body is no more than 1 / 4 of the total axial length of the embolization implant, respectively, when expanded in a natural state.

[0022] In an embodiment, the diameter of the braided wire in the stent body is 0.0008in-0.002in, and the number of the braided wire is 48-144.

[0023] In the embolization implant provided by the present application, it comprises a flow blocking component and a self-expandable braided stent body; the flow blocking component is arranged on the stent body; the embolization implant has an expanded state and a stretched state, and can switch between the expanded state and the stretched state; wherein the embolization implant forms a circumferentially non-closed double-layer curved surface structure after expansion. When configured in this way, the embolization implant of the stent type can be self-expanded without the aid of a balloon for expansion, so that the entire embolization implant has good flexibility, which can be applied not only to non-tortuous blood vessels but also to tortuous blood vessels, and thus can be adapted to patients with tortuous or non-tortuous arteries, thereby expanding the application range of the embolization implant in the treatment of carotid-cavernous fistula. In addition, the circumferentially non-closed double-layer curved surface structure makes the embolization implant have better vascular compliance, so that the embolization implant can adapt to more tortuous blood vessels and blood vessel sizes, and secondly, the surface area of the embolization implant in the expanded state is smaller, which can reduce the impact of blood flow on the position of the embolization implant, reduce the risk of displacement of the embolization implant, and the non-circumferentially closed embolization implant can reduce the coverage of normal blood vessels, reduce thrombosis, and thus reduce the risk of vascular restenosis. Not only that, the embolization implant forms a circumferentially non-closed double-layer curved surface structure after expansion, so that the distal end and the proximal end of the embolization implant are easy to open during release, improving the success rate of release and reducing the difficulty of release operation. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0025] Figure 1 is a view of the implant for embolization provided by an exemplary embodiment of the present application in an expanded state;

[0026] Figure 2 is a view of the implant for embolization provided by an exemplary embodiment of the present application in an expanded state;

[0027] Figure 3 is a view of the implant for embolization provided by an exemplary embodiment of the present application in an expanded state;

[0028] Figure 4 is a simple view of the application scenario of the implant for embolization provided by an exemplary embodiment of the present application;

[0029] Figure 5 is an end view of the implant for embolization provided by an exemplary embodiment of the present application from the direction parallel to the longitudinal axis;

[0030] Figures 6 to 8 are respectively profile shape views of the distal bevel or the proximal bevel of the implant for embolization provided by an exemplary embodiment of the present application.

[0031] In the drawings: 100-implant for embolization; 101-outer layer mesh surface; 102-inner layer mesh surface; 110-stent main body; 111-distal end; 111a-distal end part; 112-proximal end; 112a-proximal end part; 113-proximal end connecting part; 130-flow blocking part; 10-arc profile; 20-V-shaped profile; 31-fistula; 32-blood flow direction; 201-push rod. DETAILED DESCRIPTION

[0032] In order to make the purpose, advantages and features of the present application more clear, the following will make further detailed description of the present application in combination with the drawings and specific embodiments. It should be noted that the drawings are all very simplified and not drawn in proportion, and are only used to facilitate and clearly assist the purpose of explaining the embodiments of the present application. In addition, the structures shown in the drawings are often part of the actual structures. In particular, the emphasis of each drawing needs to be different, and sometimes different proportions are used.

[0033] As used in the present disclosure, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. The term "or" is generally employed in its sense including "and / or" unless the content clearly dictates otherwise. The term "plurality" is generally employed in its sense including "at least one" unless the content clearly dictates otherwise. The term "at least two" is generally employed in its sense including "two or more" unless the content clearly dictates otherwise. In addition, the terms "one end" and "the other end" and "proximal" and "distal" generally refer to two portions that are opposite each other, which includes not only the end points. The terms "proximal" and "distal" are defined herein with respect to the embolization implant, with the term "proximal" referring to the end closer to the operator of the embolization implant, i.e., the end further away from the heart, and the term "distal" referring to the end further away from the operator of the embolization implant, i.e., the end closer to the heart.

[0034] In addition, as used in the present disclosure, "mounting", "connecting", "connection", one element "disposed" in another element should be understood broadly, and generally only indicates that there is a connection, coupling, cooperation or transmission relationship between the two elements, and the connection, coupling, cooperation or transmission between the two elements can be direct or indirect through an intermediate element, and cannot be understood as indicating or implying the spatial positional relationship between the two elements, i.e., one element can be in any orientation inside, outside, above, below or one side of another element, unless the content clearly indicates otherwise. For those skilled in the art, the specific meaning of the above-mentioned terms in the present disclosure can be understood according to the specific circumstances. In addition, directional terms such as above, below, up, down, upward, downward, left, right, etc. are used with respect to the exemplary embodiments as they are shown in the figures, upward or upward direction is toward the top of the corresponding figure, and downward or downward direction is toward the bottom of the corresponding figure. In addition, herein, the term "axial" refers to a direction parallel to the longitudinal axis of the embolization implant, i.e., the length direction of the embolization implant along the direction of extension in the blood vessel is the axial direction; "radial" or "lateral" refers to a direction perpendicular to the longitudinal axis of the embolization implant, or the diameter direction of the blood vessel, i.e., the thickness or diameter direction of the stent body; "circumferential" refers to a direction around the longitudinal axis of the embolization implant; the term "not less than" means greater than or equal to the number; "not more than" means less than or equal to the number; "more than" means greater than the number.

[0035] The present disclosure will be further described below in conjunction with the accompanying drawings and preferred embodiments. In the case of no conflict, the embodiments described below and the features in the embodiments can be supplemented or combined with each other.

[0036] Figure 1 is a view of the embolization implant provided by an exemplary embodiment of the present disclosure in an expanded state, Figure 2 is a view of the embolization implant provided by an exemplary embodiment of the present disclosure in an expanded state, Figure 3is a view of the embolization implant provided by an exemplary embodiment three of the present application in an expanded state, Figure 4 is a simple view of the application scenario of the embolization implant provided by an exemplary embodiment three of the present application, Figure 5 is an end view of the embolization implant provided by an exemplary embodiment of the present application from a direction parallel to the longitudinal axis, Figures 6 to 8 are respectively profile shape views of the distal bevel or the proximal bevel of the embolization implant provided by an exemplary embodiment of the present application.

[0037] Reference is first made to Figures 1 to 4 The preferred embodiment of the present application provides an embolization implant 100 for implanting in the body to treat carotid-cavernous fistula and achieve embolization of the fistula opening 31. The embolization implant 100 comprises a self-expandable braided stent body 110, i.e., the stent body 110 can be self-expanded without the aid of a balloon. The embolization implant 100 further comprises a flow-blocking component 130 arranged on the stent body 110, and the main function of the flow-blocking component 130 is to block blood flow into the fistula opening 31. It should be noted that the flow-blocking component 130 is arranged on the stent body 110, which can be understood as including that the flow-blocking component 130 is arranged on the outer surface and / or the inner surface of the stent body 110, and the flow-blocking component 130 is arranged between two layers of stents, such as the flow-blocking component 130 is arranged between the inner layer mesh surface and the outer layer mesh surface. When configured in this way, since the stent body 110 is a braided stent, the entire embolization implant 100 has good flexibility, which can be applied not only to non-tortuous blood vessels but also to tortuous blood vessels, and therefore can be adapted to patients with arterial tortuosity or non-tortuosity, thereby expanding the application range of the embolization implant 100 in treating carotid-cavernous fistula. The wire diameter of the braided wire in the stent body 110 can be 0.0008in-0.002in, and the number of braided wires can be 48-144, so that the embolization implant 100 not only has good flexibility but also has strong support.

[0038] The material for preparing the stent body 110 is not particularly limited, such as a metal material with shape memory function, including but not limited to nickel-titanium (Ni-Ti) alloy, nickel-titanium-cobalt alloy (Ni-Ti-Co), and the like, or a polymer material with certain shape recovery ability, such as poly-p-dioxanone (PDO), poly(lactide-co-ε-caprolactone) (PLC), polyurethane (PU), and poly (norbornene) amorphous polymer, and the like. The stent body 110 can be prepared from one material or a combination of multiple materials. The stent body 110 can be braided from double-layer composite braided wire (DFT), which is composed of a core wire and a sleeve wrapped around the core wire. The sleeve can be made of a metal material with shape memory function, and the core wire can be made of a radiopaque metal material, such as platinum, iridium, tungsten, and the like. In practice, the stent body 110 can be prepared by pre-shaping the braided mesh tube, which can be pre-shaped into a stent body 110 with a specific shape by a mold.

[0039] The embolization implant 100 has an expanded state and a stretched state, and can switch between the expanded state and the stretched state. The stretched state is usually the state of the embolization implant 100 in the catheter (including microcatheter), which has no specific shape, such as a long strip winding shape. The expanded state is usually the state of the embolization implant 100 after being separated from the catheter or the natural state. The natural state is the state of the embolization implant 100 when it is not constrained by external force, such as the natural expansion state outside the blood vessel.

[0040] In addition to the above settings, the embolization implant 100 is also configured to form a circumferentially non-closed double curved surface structure (i.e. open loop structure) after expansion, thereby distinguishing from the balloon expandable covered stent of the traditional tubular structure. The "circumferentially non-closed" should be understood as that the entire stent body 110 or the embolization implant 100 is curved to form an opening in the circumferential direction, but the opening can be large or small, and is not specifically limited as long as it is not a closed tube. Because the stent curved surface is not circumferentially closed, the embolization implant 100 has better vascular compliance, so that the embolization implant 100 can adapt to more tortuous blood vessels and blood vessel sizes, and secondly, the surface area of the embolization implant 100 in the expanded state is smaller, which can reduce the impact of blood flow on the position of the embolization implant 100, reduce the risk of displacement of the embolization implant 100, and the non-circumferentially closed embolization implant 100 can reduce the coverage of normal blood vessels, reduce thrombosis, thereby reducing the risk of vascular restenosis, and ultimately reducing the risk of displacement of the entire embolization implant 100 and ischemic complications. Not only that, after the embolization implant 100 expands to form a circumferentially non-closed double curved surface structure, the distal end 111 and the proximal end 112 of the embolization implant 100 are easily opened during release, improving the success rate of release and reducing the difficulty of release operation.

[0041] It should be understood that the conventional balloon expandable covered stent is mostly formed by cutting a metal pipe, and has a tubular structure, and the distal end and the proximal end are both closed circumferential surfaces. The entire covered stent is relatively hard and has poor flexibility, and it is difficult to pass through the tortuous internal carotid artery to reach the lesion site. Moreover, the tubular stent is subjected to a large radial pressure when transported in the catheter, which causes the distal end and the proximal end to easily interfere or entangle with each other, and further causes the proximal end and the distal end of the stent to not be easily opened when the stent is released. Generally, the position needs to be adjusted multiple times, which not only increases the difficulty of the operation, but also prolongs the operation time.

[0042] Compared with the conventional balloon expandable covered stent, the embolization implant 100 provided in the present application is formed by braiding the stent body 110, and the stent body 110 or the embolization implant 100 can form a circumferentially non-closed double curved surface structure when expanded. Therefore, even if it is compressed in the catheter for transportation, the proximal end 112 and the distal end 111 of the stent body 110 or the embolization implant 100 are not easily entangled or interfered with each other, so that the proximal end 112 and the distal end 111 can be smoothly opened when released without the need to adjust the position of the stent multiple times. Therefore, the release process of the embolization implant 100 provided in the present application is simpler, which is convenient for medical staff to adjust the position of the stent, reduces the difficulty of the operation, and the circumferentially non-closed double curved surface structure can be applied to smaller catheters (including microcatheters) for transportation, reduces the occurrence of complications in the operation process, and can be adapted to more blood vessel sizes, and has a wider application range.

[0043] It should also be understood that the shape of the double-layer curved surface structure is adapted to the curved surface shape of the intravascular lumen at the carotid cavernous fistula, i.e. the target lumen, so that the embolization implant 100 can better adhere to the blood vessel wall at the carotid cavernous fistula after expansion, and be supported in the blood vessel without displacement by the force acting on the blood vessel wall. Therefore, the embolization implant 100 in the present application is anchored in the blood vessel by its own expansion force, without the need for additional support structure for fixation, and it can also be understood that the maximum size of the expanded embolization implant 100 is larger than the size of the lumen, so that it can be stably anchored in the blood vessel. In this article, the circumferential direction of the embolization implant 100 corresponds to the circumferential direction of the blood vessel, and the longitudinal axis of the embolization implant 100 corresponds to the extension direction of the blood vessel. The embolization implant 100 is used to extend and spread along the circumferential direction of the blood vessel to form the double-layer curved surface structure with the circumferential direction not being closed, and to form a distal opening and a proximal opening along the axial direction of the blood vessel to pass through the blood flow.

[0044] Please refer to Figure 5 , the cross section of the double-layer curved surface structure is a closed torus, more specifically, the stent body 110 has an outer layer mesh surface 101 (i.e. outer layer curved surface) and an inner layer mesh surface 102 (i.e. inner layer curved surface) oppositely arranged along the radial direction of itself, the outer layer mesh surface 101 is used to block the fistula 31 and adhere to the blood vessel wall, the inner layer mesh surface 102 is arranged away from the fistula 31, and the inner layer mesh surface 102 and the outer layer mesh surface 101 are connected to each other to form the closed torus. As actually made, the whole braided mesh tube can be flattened by using a mold and subjected to preforming treatment to form the double-layer curved surface structure with the circumferential direction not being closed. The arrangement of such double-layer dense mesh surface can form a dense plug, improve the blocking efficiency, and has good supportability and is not easy to displace. Especially, a flow blocking component 130 can be arranged between the two layers of mesh surfaces.

[0045] The flow blocking component 130 can be attached to the outer layer mesh surface 101 and / or the inner layer mesh surface 102 of the stent body 110, or arranged in the closed torus defined by the outer layer mesh surface 101 and the inner layer mesh surface 102. The flow blocking component 130 is preferably made of a film to obtain a smaller thickness of the embolization implant 100 and reduce the risk of thrombosis. The film material for preparing the flow blocking component 130 is a medical polymer material with good biocompatibility, such as PET material (polyethylene terephthalate), PTFE (polytetrafluoroethylene), polylactic acid (PLA), or polycaprolactone (PCL), or a blend of the two, polyurethane (TPU), and the like.

[0046] The surface of the flow blocking member 130 can be modified, for example, a drug coating is provided on the surface of the flow blocking member 130, which includes a drug and a drug carrier, wherein the type of the drug is not limited, for example, the drug is an anticoagulant drug, an anti-platelet drug, etc. The inner surface and / or the outer surface of the flow blocking member 130 is provided with a drug coating, which can further prevent thrombosis, thereby further reducing the risk of stenosis in the embolic implant. In a non-limiting embodiment, the drug can be selected from paclitaxel, rapamycin and derivatives, and the drug carrier can be selected from iopromide, polyvinylpyrrolidone (PVP), urea, shellac, triglyceride, BTHC, etc. It should be understood that the inner surface of the flow blocking member 130 refers to the surface away from the outer layer mesh surface 101, and the outer surface of the flow blocking member 130 refers to the surface close to the outer layer mesh surface 101.

[0047] In a preferred embodiment of the present application, the flow blocking member 130 is arranged in the closed loop surface defined by the inner layer mesh surface 102 and the outer layer mesh surface 101, so as to be clamped and fixed by the closed loop surface. In this way, the flow blocking member 130 is less likely to fall off or shift, thereby effectively reducing the risk of internal leakage. It should be noted that the inner layer mesh surface 102 and the outer layer mesh surface 101 can be directly pressed and adhered together, or a certain gap can be formed, and the size of the gap is not limited. In addition, when the flow blocking member 130 is arranged in the closed loop surface, the inner layer mesh surface 102 and the outer layer mesh surface 101 should have sufficient clamping force to clamp the flow blocking member 130.

[0048] The flow blocking member 130 is further preferably fixedly connected to the proximal end 112 and / or the distal end 111 of the stent body 110 in the axial direction, for example, by suturing, heat melting, adhesive bonding, etc. It should be understood that in the embodiments of the present application, the flow blocking member 130 can be clamped and fixed only by the clamping force of the two layer mesh surfaces, or in addition to the clamping force of the two layer mesh surfaces, the flow blocking member 130 can be further fixedly connected to the stent body 110, and generally the proximal end 112 and / or the distal end 111 of the stent body 110 can be fixedly connected, so as to further prevent the flow blocking member 130 from shifting or falling off.

[0049] It is also known that the conventional balloon-expandable covered stent is coated with a film material on the outer surface of the tubular stent by electrospinning technology. In this case, the film material is prone to fall off or shift, which not only is not firmly fixed and increases the risk of internal leakage, but also has poor consistency with the expansion of the stent, affecting the flexibility of the entire covered stent. Compared with the conventional balloon-expandable covered stent, the application clamps the flow resistance component 130 between the two layers of mesh and can be further fixedly connected with the stent body 110. In this way, the fixation of the flow resistance component 130 is more secure and less prone to shift, and the risk of internal leakage is low. Moreover, the flow resistance component 130 can better follow the stent body 110 to shrink or expand synchronously. In actual production, the flow resistance component 130 is separately formed and then inserted between the two layers of mesh, such as by electrostatic spraying or immersion.

[0050] Further, the thickness of the flow resistance component 130 needs to be optimized. If the thickness of the flow resistance component 130 is too large, it will increase the thickness of the entire embolization implant 100, and if the thickness of the flow resistance component 130 is too small, it will be difficult to form in the process. In order to solve these problems, the thickness of the flow resistance component 130 is preferably 5 μm to 100 μm, and more preferably 5 μm to 50 μm. This thickness range makes it easy to process the flow resistance component 130 in the process, and also makes the thickness of the embolization implant 100 not too large, which helps to reduce the resistance to delivery and reduce the impact on blood flow after the embolization implant 100 is implanted. The flow resistance component 130 can be made of degradable or non-degradable film. When a degradable film is used, it is convenient to slowly release the drug.

[0051] The proximal end 112 of the stent body 110 is used for releasable connection with the push rod 201, and the release mode between the two is not limited, such as electrolytic release, mechanical release or heat melting release. The proximal end 112 can be provided with a proximal end connecting portion 113, which is connected with the push rod 20. The proximal end connecting portion 113 can be further provided as a developing structure, such as a developing sleeve or a developing spring.

[0052] The distal end portion 111a of the stent body 110 is preferably provided as a distal end bevel (i.e. an inclined distal end opening) extending axially to the distal end. The provision of the distal end bevel reduces the pushing resistance during stent release, allowing the embolization implant 100 to better expand along the blood vessel wall and adhere to the blood vessel wall, while also reducing blood flow (see Figure 4the impact of blood flow on the stent, and further reduce the risk of migration. Further, all the braided wires on the stent body 110 are back-wound at the distal end 111 of the stent body along the axial direction to form a smooth edge distal end face without forming a braided ring, and the braided wires are tightened to avoid protruding outwards. In this way, when the embolization implant 100 is transported in the catheter, there is no problem of mutual interference or mutual entanglement caused by the protruding free wire heads of the braided wires at the distal end face, and the risk of the distal end 111 failing to open is further reduced. It can also be understood that the edge of the distal chamfer is smooth without protrusions, and the edge of the distal chamfer can be an arc or a straight line or a combination of a straight line and an arc. It should also be understood that the slope surface of the distal chamfer is a closed ring surface.

[0053] The shape of the distal chamfer is not limited in the present application. As in the illustrative embodiment, referring to Figure 6 , the distal chamfer of the distal end portion 111a has an arc-shaped profile 10, and the left and right curved surfaces are smoothly connected at the bottom. As in another illustrative embodiment, referring to Figure 7 , the distal chamfer of the distal end portion 111a has a V-shaped profile 20, and the bottom of the V-shaped profile 20 is not smoothly connected. In other illustrative embodiments, referring to Figure 8 , the bottom of the V-shaped profile 20 is smoothly connected by a circular arc. As in the present embodiment, the edges of the distal chamfer are all smoothly connected, such as using the schemes of Figure 6 and Figure 8 to achieve smooth transition of the left and right curved surfaces at the bottom to avoid sharp areas at the intersection of the left and right curved surfaces to damage the blood vessel.

[0054] The proximal end portion 112a of the stent body 110 is preferably a proximal chamfer (i.e., an inclined proximal opening) extending along the axial direction towards the proximal end 112. The provision of the proximal chamfer is beneficial to reduce the impact of proximal blood flow on the embolization implant 100, further reduce the risk of migration of the embolization implant 100, and make the embolization implant 100 easier to be pulled into the catheter for re-recovery and release. Further, all the braided wires on the stent body 110 form free wire heads at the proximal end 112 of the stent body along the axial direction, and all the free wire heads converge and are fixed by the proximal connecting portion 113. Therefore, all the braided wires are back-wound at the distal end 111 to return to the proximal end 112 to form free wire heads, and after all the free wire heads are fixed together, it is convenient to connect with the push rod 201. Further, the radiopaque structure wraps all the free wire heads. Further, the flow-blocking component 130 is fixedly connected with the proximal connecting portion 113.

[0055] The shape of the proximal chamfer is not limited in the present application, and the proximal chamfer can adopt a similar shape to the distal chamfer. For details, please refer to Figures 6 to 8As shown, further explanation is not provided here. In some embodiments of this application, the free ends of all the braided yarns on the outer mesh surface 101 or the inner mesh surface 102 at the near end bevel converge at the bottom where the two curved surfaces intersect to form a near end connection 113. That is, the nearest end of the support body 110 converges to form the near end connection 113 and connects to the push rod 201.

[0056] The curvature of the double-layer curved surface structure is adapted to the diameter of the target lumen (i.e., blood vessel). In embodiments of this application, during natural expansion, the curvature of the double-layer curved surface structure is not less than 2 / 3π, preferably not exceeding π, such as 2 / 3π, 3 / 4π, or π. Furthermore, during expansion under the constraint of the target lumen, the curvature of the double-layer curved surface structure exceeds π. That is, when anchored within the blood vessel, due to the constraint of the lumen diameter, the double-layer curved surface structure is folded and compressed, resulting in a curvature greater than π. Additionally, as... Figure 5 As shown, the surface curvature corresponds to the central angle α, which should be understood as the ratio of the arc length to the radius of the contour curve of the cross-section (i.e., the cross-section) of the surface. This design ensures that the left and right curved surfaces of the double-layered surface structure can extend beyond the axis of the blood vessel. While ensuring sufficient support for the embolization implant 100, it also ensures that the embolization implant 100 has a certain adaptability to different blood vessel diameters, allowing for adaptive anchoring. The embolization implant 100 of this invention does not require auxiliary stents for support, resulting in a simpler structure, more convenient surgical operation, and lower surgical risk.

[0057] In some embodiments, the cross-section of the double-layer curved surface structure is a closed torus, and the flow-blocking component 130 is clamped within the closed torus. For example... Figure 5 As shown, this closed torus can be an approximately bowl-shaped closed torus. It is understood that the shape of the closed torus is not limited to this; it can be any shape. Figures 6-8 The examples shown include approximately U-shaped closed toruses and approximately V-shaped closed toruses.

[0058] The total axial length of the embolization implant 100 when expanded in its natural state is set according to the size of the fistula 31 to be sealed. In this embodiment, the total axial length of the embolization implant 100 when expanded in its natural state is 15mm to 55mm, such as 15mm, 30mm, 40mm, 50mm, or 55mm. This total axial length allows the embolization implant 100 to adapt to most fistula sizes. In this embodiment, the maximum diameter of the embolization implant 100 when expanded in its natural state can be 3mm to 6mm, such as 3mm, 4mm, 5mm, or 6mm, to suit the blood vessel sizes of most patients. It should be understood that the axial length of the embolization implant 100 generally changes in the same direction as its curved surface diameter. If the axial length is shorter, the curved surface diameter is also smaller; therefore, the curved surface diameter can be adjusted according to the axial length.

[0059] To ensure that the middle portion of the stent body 110 has sufficient dimensions to cover the fistula 31 and support the vessel wall, without increasing the overall axial length of the implant, preferably, when expanded in its natural state, the axial lengths of the distal portion 111a and the proximal portion 112a do not exceed 1 / 4 of the total axial length of the embolization implant 100, such as 1 / 6, 1 / 5, or 1 / 4. It should be understood that, in this embodiment, the stent body 110 has a distal portion 111a and a proximal portion 112a, and an intermediate portion located between the proximal portion 112a and the distal portion 111a. This intermediate portion serves as the occlusion body to seal the fistula 31, and the proximal portion 112a and the distal portion 111a are positioned on either side of the fistula 31. The proximal end 112 is generally understood as the closest point of the stent body 110, and the distal end 111 is generally understood as the furthest point of the stent body 110.

[0060] The structure of the embolization implant 100 provided in the embodiments of the present invention will be further illustrated below.

[0061] In one specific implementation, such as Figure 1 As shown, in the expanded state, the distal portion 111a is a distal bevel, which is an arc-shaped bevel; the proximal portion 112a is a proximal bevel, which is also an arc-shaped bevel; furthermore, the flow-blocking component 130 ( Figure 1(Unmarked) A PTFE film is used and fixed between the double-layer mesh of the stent body 110. No drug coating is applied to the surface of the PTFE film. Furthermore, the curvature of the stent body 110 when naturally expanded is π, and the total axial length of the stent body 110 when naturally expanded is 30 mm. The axial lengths of the distal portion 111a and the proximal portion 112a are each 1 / 6 of the total axial length of the stent body 110. In this embodiment, the axial lengths of the proximal and distal bevels are relatively short, and the proximal and distal bevels transition smoothly to the middle portion, resulting in an almost smooth edge for the entire stent body 110.

[0062] In another specific implementation, such as Figure 2 As shown, in the expanded state, the distal portion 111a is a distal bevel, which is a V-shaped bevel with a smooth transition at the bottom; the proximal portion 112a is a proximal bevel, which is a V-shaped bevel extending from the bottom to form the proximal connection portion 113; furthermore, the flow-blocking component 130 is made of PLA film (… Figure 2 (Not labeled), and disposed between the double-layer mesh, the surface of the PLA film is coated with rapamycin, which has an antiplatelet effect and can reduce the risk of stenosis within the embolization implant. In this case, the PLA film can degrade over time, achieving sustained drug release. Furthermore, the curvature of the stent body 110 when expanded in its natural state is 3 / 4π, and the axial length of the proximal portion 112a is 1 / 5 of the total axial length of the stent body 110, increasing the axial length of the proximal portion 112a compared to the previous embodiment. In this embodiment, the distal bevel has a straight edge, which can increase the effective coverage area of ​​the embolization implant, while the proximal bevel is steeper than the distal bevel. The steepness is due to the formation of the proximal connection portion 113, which allows the proximal bevel to more effectively reduce the impact of blood on the stent and facilitates catheter return.

[0063] In other specific implementations, such as Figure 3As shown, in the expanded state, the distal end portion 111a is a distal end bevel, which is a circular arc bevel, the proximal end portion 112a is a proximal end bevel, which is a V-shaped bevel with the bottom extended to form a proximal end connecting portion 113; in addition, the flow blocking component 10 is made of TPU film, which is arranged between the double-layer curved surfaces of the stent body 110, and the surface of the TPU film is not provided with a drug coating; in addition, the curved surface of the stent body 110 has a curvature of 2 / 3π when it is expanded in the natural state, and the axial lengths of the distal end portion 111a and the proximal end portion 112a are respectively 1 / 4 of the total axial length of the stent body 110. Compared with the above two embodiments, the flow blocking component 130 in this embodiment has better shape resilience due to the use of TPU material, and is more consistent with the stretching and expansion of the stent body 110, so that the overall compliance of the embolization implant 100 can be improved.

[0064] As shown, Figure 4 As shown, the embolization implant 100 provided by the present application is fully expanded after reaching the lesion site, the double-layer curved surfaces are tightly attached to the blood vessel wall, and the fistula 31 is covered by the dense mesh surface of the middle portion, wherein the distal end bevel of the distal end portion 111a is provided without damage, and the proximal end bevel of the proximal end portion 112a has a longer axial length and a smaller surface area, which effectively reduces the impact of blood flow on the stent.

[0065] In summary, the embolization implant provided by the present application is a woven curved embolization implant, which has the characteristics of self-expansion and circumferential non-closed curved surface, which can improve the vascular compliance of the embolization implant, and can also be applied to tortuous blood vessels. The embolization implant has a circumferential non-closed curved surface structure, which can also adapt to the diameter of the blood vessel, thereby adapting to more blood vessel sizes. At the same time, the embolization implant can also reduce the contact area between the stent and the blood vessel, thereby reducing the risk of blood vessel stenosis. In addition, the flow blocking component is preferably located between the two layers of mesh surfaces, so that the shape of the embolization implant can be better restored, effectively reducing internal leakage and improving fistula occlusion rate. In addition, the two ends of the embolization implant can adopt a bevel, which can reduce the impact of blood flow on the embolization implant, reduce the possibility of displacement of the embolization implant, and reduce the risk of recurrence. Secondly, the embolization implant can be loaded with drugs such as anti-platelet drugs through the flow blocking component, thereby reducing the incidence of postoperative ischemic complications. In addition, compared with a single-layer mesh surface, the metal coverage rate of the fistula is improved, which is beneficial to the endothelialization process and accelerates the healing of the wound.

[0066] It should also be understood that the above discloses the preferred embodiments for implementing the present application, but the present application is not limited to the scope disclosed by the above embodiments, any transformation on the basis of the structure provided by the above embodiments belongs to the scope protected by the present application, and those skilled in the art can deduce from the above embodiments.

Claims

1. An embolization implant for treating carotid-cavernous fistula, characterized in that, It includes a flow-blocking component and a self-expanding braided stent body; the flow-blocking component is disposed on the stent body; the embolization implant has an expanded state and a stretched state, and can switch between the expanded state and the stretched state; The embolization is expanded by the implant to form a circumferentially open double-layer curved surface structure; the cross-section of the double-layer curved surface structure is a closed annular surface, and the flow-blocking component is clamped in the closed annular surface; the shape of the double-layer curved surface structure is adapted to the shape of the vascular lumen of the internal carotid cavernous fistula; the curvature of the double-layer curved surface structure is adapted to the diameter of the target lumen.

2. The embolization implant according to claim 1, characterized in that, The flow-blocking component is connected to the proximal and / or distal ends of the support body along the axial direction.

3. The embolization implant according to claim 1, characterized in that, The distal end of the support body is divided into a distal bevel extending axially to the distal end.

4. The embolization implant according to claim 1 or 3, characterized in that, All the braided wires on the support body are wound around the distal end of the support body along the axial direction to form a smooth distal end face.

5. The embolization implant according to claim 1, characterized in that, The proximal end of the support body is divided into a proximal bevel extending axially towards the proximal end.

6. The embolization implant according to claim 1 or 5, characterized in that, All the braided filaments on the support body form free filament heads at the proximal end of the support body along the axial direction, and all the free filament heads converge and are bound and fixed by the proximal end connection.

7. The embolization implant according to claim 6, characterized in that, The proximal connector is a developing structure that surrounds all the free filament ends.

8. The embolization implant according to claim 1 or 2, characterized in that, The inner and / or outer surfaces of the flow-blocking component are provided with a drug coating.

9. The embolization implant according to claim 8, characterized in that, The flow-blocking component is made of a biodegradable thin film.

10. The embolization implant according to claim 1 or 2, characterized in that, The flow-blocking component is made of a thin film with a thickness of 5 μm to 100 μm.

11. The embolization implant according to claim 10, characterized in that, The thickness of the film is 5μm to 50μm.

12. The embolization implant according to claim 1, characterized in that, When expanded in its natural state, the curvature of the double-layer curved surface structure is not less than 2 / 3π.

13. The embolization implant according to claim 12, characterized in that, When expanding under natural conditions, the curvature of the double-layer curved surface structure does not exceed π, and when expanding under the constraint of the target cavity, the curvature of the double-layer curved surface structure exceeds π.

14. The embolization implant according to claim 1, characterized in that, The total axial length of the embolization implant when it expands in its natural state is 15mm to 55mm, and / or the maximum diameter of the embolization implant when it expands in its natural state is 3mm to 6mm.

15. The embolization implant according to claim 1, characterized in that, When expanded in its natural state, the axial length of the proximal and distal portions of the stent body does not exceed 1 / 4 of the total axial length of the embolization implant.

16. The embolization implant according to claim 1, characterized in that, The diameter of the braided filaments in the main body of the support is 0.0008in to 0.002in, and the number of braided filaments is 48 to 144.

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